1. Technical Field of the Invention
The present invention relates to a method and an apparatus for freezing a surface layer of a food product.
2. Prior Art
When freezing products that do not have a fully solid structure, the products can easily mould to the base, on which they are frozen. This is disadvantageous if the base has a shape that differs from the one that is desirable for the product in its final frozen form. There is also a risk that the products freeze onto the base, which results on the one hand in the product being defective and, on the other hand, in residues of the product remaining on the base and needing to be removed before the base can be used again.
It is known that freezing fast can be avoided if the base is given a very low temperature. This is, however, a relatively energy-consuming method as it requires liquid nitrogen or the like. Alternatively, a foil can be used between the base and the product, in which case the product need not have such a low temperature. However, the heat transmission will then be relatively poor especially if the product is not so soft that a major part of its lower surface presses the foil into direct contact with the base.